Disposable diaphragm valve

ABSTRACT

A valve for dispensing fluid as a bead or a dot having a housing with an internal cavity and a disposable insert positioned within the cavity of the housing having a fluid inlet, a fluid chamber, a fluid outlet and a diaphragm adjacent the fluid chamber between the fluid inlet and the fluid outlet. The replaceable insert further has a latching mechanism adjacent the diaphragm for receipt of a reciprocating actuator to actuate the diaphragm to dispense fluid from the fluid chamber.

BACKGROUND OF THE INVENTION

The present invention relates to disposable valves and more particularlyto an actuator controlled diaphragm valve having a valve insert made outof a moldable plastic having a fluid chamber and a diaphragm componentcapable of controlled, repeatable and accurate dispensing of fluidmaterials of various types and viscosities and in various forms, such asbeads, dots and the like.

Positive displacement rotary microvalves are known for dispensing fluidmaterials such as adhesives, epoxies, potting compounds, SMT adhesives,two-part adhesives, silver and gold filled adhesives, UV curableadhesives, and solder pastes in a repeatable and accurate manner.Typically, these dispensers for fluid material are used in a widevariety of industries, such as electronic assembly and repair, form inplace gasketing, component assembly and sealing, mold-making, casting,tool and machine and equipment fabrication and assembly, and a varietyof other uses.

Prior dispensing devices typically include a gear motor which controlsthe rotation of a feed screw supported in a housing. Fluid is fed to thehousing from an external pressure on the fluid and to force the fluidmaterial into the housing. Supported in the housing for rotation by themotor is a feed screw or auger which urges the fluid material into adispensing tip which is affixed to the output end of the housing. Thedispensing tip is essentially in the form of a pointless needle which islocked and sealed to the output end of the housing.

The valve includes a rotary screw of a variable pitch type whichhomogenizes low viscosity material and which compresses the material toreduce its volume. A one piece housing having a sleeve located in thebore and which extends only partly up the bore area. The housing alsoincludes a passageway formed in the housing through which the fluidflows and which is in contact with the passage wall as the fluid isurged into the bore. The portion of the bore above the sleeve may becontacted with the fluid since there is no seal between the upperportion of the bore and the sleeve. The housing also includes a screwwhich holds a dispensing coupling and thus the sleeve and the bore, agasket being provided between the dispensing coupling and the lowerportion of the sleeve.

Although prior microvalve dispensers operate satisfactorily, there arecircumstances which require improvements which can be made. For example,dispensers are normally used continuously in assembly line andcommercial operations except during lunch breaks and after a shift isover. If the material being dispensed hardens in the microvalve ordegrades for any reason, then the valve has to be cleaned out and thisis a difficult operation. Should such hardening occur, the unit is oftensent back to the supplier for cleaning and thus may be expensive andcreate considerable down time. In addition, materials being dispensedmay change during operation and it may be the case that later dispensedmaterial is contaminated by that previously dispensed or is incompatiblewith the previously dispensed material. In such a case, thecontamination must be cleaned out of the valve, which also can lead toconsiderable expense and down time for cleaning.

Consequently, improvements to address these issues were developed suchthat all interior surfaces that come into contact with fluid beingdispensed were readily replaceable therefore reducing costs of cleaningand repair and reducing down time in assembly and commercial operations.Such microvalve devices included a conventional gear driven motor unitto which was mounted a housing for the valve. Supported within thehousing was a disposable insert chamber which forms the interior wetsurfaces of the dispenser. The insert includes a feed arm through whichfluid under pressure from an external source is fed to the interior ofthe insert and thus the fluid does not contact the feed arm surfaces ofthe housing of the microvalve. Located in the insert is a feed mechanismconnected to and driven by the motor, to dispense a measured amount offluid accurately and controlled by the motor. Such prior disposableinserts required a motor having and output shaft for driving a helicalscrew or auger supported for rotation in the insert. Fluid in a measuredamount, depending on the rotational speed and configuration of the screwwas urged out of the outlet which forms the exit passageway for theinsert. Although such disposable rotary microvalve insert configurationworks well, having to include a helical screw or auger supported forrotation within the insert is a complicated mechanism adding to thecomplexity and expense of the insert which is disposable. Consequently aneed exists for a simplified disposable valve insert which is lessexpensive to manufacture yet provides consistent and reliableperformance.

SUMMARY OF THE INVENTION

The present invention is directed to a disposable actuator controlleddiaphragm valve insert which addresses the drawbacks of prior disposableinsert designs. The present invention provides a relatively simplemicrovalve structure in which all of the interior surfaces which comeinto contact with the fluid being dispensed are readily replaceabletherefore reducing cost of cleaning and repair in reducing down time inassembly in commercial operation.

In accordance with the present invention, the microvalve includes anactuator unit to which is mounted a housing for the valve. Supportedwithin the housing is the disposable insert chamber which forms theinterior wet surfaces of the dispenser. The valve insert includes a bodysection through which the fluids such as adhesives, epoxies, solderpaste, etc. are accurately dispensed as a dot or bead. The disposableinsert is made out of a moldable or machinable plastic compound andincludes both a fluid chamber and a diaphragm component which are joinedand sealed together by either ultra-sonic, laser or spin weldingprocesses or they can be glued or snap-fitted together. The insert hasfluid inlet and outlet passages which extend beyond the valve body.Attached to the outlet passage is a removable and replaceable dispensingtip.

When the insert is installed into the valve body, the diaphragm head isengaged with an actuator. When the actuator is reciprocating, thediaphragm will move in the same motion and thus fluid will be dispensed.

A latching feature may be provided on the diaphragm component with ascrew, rod or other material insert for added strength. The diaphragmcomponent can be made with additives in the base moldable plastic tochange the strength and compliance of the diaphragm component.Additionally, the fluid chamber component is made of a material whichfacilitates the joining of the fluid chamber and diaphragm components.

These and other aspects and advantages of the present invention willbecome apparent with the following specification, which, together withthe accompanying drawings describes and illustrates embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of the microvalve dispenser ofthe present invention;

FIG. 2 is a bottom view of the dispenser of FIG. 1;

FIG. 3 is a side view of the disposable valve insert of FIG. 1; and

FIG. 4 is a side view of the dispenser of FIG. 1 illustrated in partialsection.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1 through 3, a microvalve dispenser assembly 10 isillustrated. The assembly includes an actuator 12 having a housing 14mounted thereon. A mounting bracket 16 is supported by the actuator formounting various dispensed material sources. The actuator may be any oneof either a pneumatic or hydraulic driven type or direct current servoor stepper motor type. The actuator may be controlled by a controllermechanism (not shown).

The housing 14, which may be of metal such as aluminum, or a corrosionresistant plastic such as acetal, for example, may be made up of a mainbody housing 14 a and a body front plate 14 b held together by captivescrews 18. The main body housing 14 a and the front body plate 14 bcooperate to form an internal cavity 20 for receipt of a disposablediaphragm valve insert 22. The insert 22 includes a fluid chambercomponent 24 and a diaphragm component 26. The fluid chamber and thediaphragm components include a joint 28 for joining and sealing thecomponents together by either an ultra-sonic, laser or spin weldingprocess or are snap-fitted or glued together. The valve insert ispreferably made out of a moldable or machinable plastic compound. Theinsert includes a fluid inlet passage 30 and a fluid outlet passage 32.The outlet passage 32 has a removable and replaceable dispensing tip 34.The diaphragm component 26 includes a latching feature 36 having anenlarged head portion 31.

The fluid inlet passage 30 includes an outer circumferential shoulder 40which extends beyond the housing and body front plate 14 b thuspreventing rotational movement of the insert relative to the housing.The outer surface is threaded 42 so that a fluid supply source may beeasily attached and removed. Similarly the fluid outlet passage 32 has ashoulder portion 44 which extends beyond a lower surface of the bodyfront plate 14 b. Shoulder 44 assists in attaching the dispensing tipsecurely.

As seen best in FIG. 4, when the disposable diaphragm valve insert 22 ispositioned within the cavity 20 of the housing 14 the head portion 38 ofthe latching feature 36 is engaged with a chuck 48 which is driven bythe actuator 12. The latching feature 36 can include an additionalstrength feature such as a screw 46 which could also be a rod or othermaterial insert. The sealing feature 56 of the diaphragm component 26 ispositioned between the latching mechanism and the fluid chambercomponent 24 such that when the chuck 48 is reciprocating the diaphragmmoves in the same motion to dispense a fluid. The fluid is dispensed bythe diaphragm opening and closing the fluid path 54 as fluid is beingpumped in the inlet under pressure. The diaphragm can be made with orwithout additives in the base moldable or machinable plastic material tochange the strength and compliance of the diaphragm as needed based uponthe fluid being dispensed. The diaphragm 26 and the feed chamber 24 canbe made of various materials such that the feed chamber and thediaphragm can be joined and sealed together. Additives to either thebase moldable plastic material or the diaphragm can be fiberglass, glassbeads, carbon fiber or elasticizers

Although the present invention has been described and illustrated withrespect to various embodiments thereof, it is to be understood thatchanges and modifications can be made herein which are within the fullintended scope of the invention as hereinafter claimed.

What is claimed is:
 1. A method of using a fluid dispensing valve assembly, comprising: based on user input, a disposable diaphragm valve insert being inserted into an internal cavity of a housing of a fluid dispensing valve assembly, the disposable diaphragm valve insert having interior surfaces which come into contact with a dispensing fluid; receiving fluid into a fluid chamber in the disposable diaphragm valve insert, a diaphragm within the disposable diaphragm valve insert being engaged and disengaged by a reciprocating actuator to move the diaphragm through the fluid chamber; dispensing the fluid when the actuator is disengaged with the diaphragm; based on user input, the disposable diaphragm valve insert being replaced, as an assembled unit, with a different disposable diaphragm valve insert, as an assembled unit.
 2. The method of claim 1, wherein the step of receiving fluid into the disposable diaphragm valve insert includes receiving fluid under pressure through a valve inlet into the fluid chamber in the disposable diaphragm valve insert.
 3. The method of claim 1, wherein the step of dispensing the fluid is through a fluid outlet connected to the fluid chamber.
 4. The method of claim 1, wherein the fluid dispensed is an adhesive, epoxy, potting compound or solder paste.
 5. The method of claim 1, wherein the disposable diaphragm valve insert further includes a latching mechanism adjacent the diaphragm opposite the fluid chamber.
 6. The method of claim 2, wherein the reciprocating actuator extends through the latching mechanism to actuate the diaphragm to dispense fluid from the fluid chamber.
 7. The method of claim 5, wherein the latching mechanism has a reinforcing member positioned therein.
 8. The method of claim 1, wherein the diaphragm is made of a plastic having strength and compliance additives.
 9. The method of claim 1, wherein the fluid chamber and the diaphragm are sealed together by welding.
 10. The method of claim 1, wherein the fluid chamber and the diaphragm are joined and sealed by spin welding, laser welding, ultra-sonic welding, thermal compression, snap-fitting or by glue.
 11. The method of claim 1, further comprising a pneumatic device attached to the housing to drive the reciprocating actuator.
 12. The method of claim 1, further including a fluid inlet and a fluid outlet connected to the fluid chamber, and the fluid inlet and the fluid outlet extend beyond the housing and further comprise a removable dispensing tip attached to the fluid outlet.
 13. The method of claim 1, wherein the housing comprises a main housing body and a front plate removably connected together to form the internal cavity. 